* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Cosmology News -> IRAS 09104+4109
Post Info TOPIC: IRAS 09104+4109
Blobrana


L

Posts: 131433
Date:
RE: IRAS 09104+4109
Permalink  
 

Title: Confirmation of the nature of the absorber in IRAS 09104+4109
Authors: Chia-Ying Chiang, E. M. Cackett, P. Gandhi, A. C. Fabian

We present the first long Suzaku observation of the hyperluminous infrared galaxy IRAS 09104+4109 which is dominated by a Type 2 AGN. The infrared to X-ray SED indicates that the source is an obscured quasar with a Compton-thin absorber. However, the 3 \sigma hard X-ray detection of the source with the BeppoSAX PDS suggested a reflection-dominated, Compton-thick view. The high-energy detection was later found to be possibly contaminated by another Type 2 AGN, NGC 2785, which is only 17 arcmin away. Our new Suzaku observation offers simultaneous soft and hard X-ray coverage and excludes contamination from NGC 2785. We find that the hard X-ray component is not detected by the Suzaku HXD/PIN (effective energy band 14-45 keV). Both reflection and transmission models have been tested on the latest Suzaku and Chandra data. The 0.5-10 keV spectrum can be well modelled by the two scenarios. In addition, our analysis implied that the absorption column required in both models is N_{H} ~ 5 x 10^{23} cm^{-2}. Unless IRAS 09104+4109 is a "changing-look" quasar, we confirm that it is a Compton-thin AGN. Although the lack of detection of X-ray emission above 10 keV seems to favour the transmission scenario, we found that the two models offer fairly similar flux predictions over the X-ray band below ~ 40 keV. We also found that the strong iron line shown in the Suzaku spectrum is in fact a blend of two emission lines, in which the 6.4 keV one is mostly contributed from the AGN and the 6.7 keV from the hot cluster gas. This implies that the neutral line is perhaps caused by disc reflection, and the reflection-dominated model is more likely the explanation. The transmission model should not be completely ruled out, but a deeper hard X-ray spectrum observation is needed to discriminate between the two scenarios.

Read more (128kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: A Giant Metrewave Radio Telescope/Chandra view of IRAS 09104+4109: A type 2 QSO in a cooling flow 
Authors: Ewan O'Sullivan, Simona Giacintucci, Arif Babul, Somak Raychaudhury, Tiziana Venturi, Chris Bildfell, Andisheh Mahdavi, J. B. R. Oonk, Norman Murray, Henk Hoekstra, Megan Donahue 

IRAS 09104+4109 is a rare example of a dust enshrouded type 2 QSO in the centre of a cool-core galaxy cluster. Previous observations of this z=0.44 system showed that as well as powering the hyper-luminous infrared emission of the cluster-central galaxy, the QSO is associated with a double-lobed radio source. However, the steep radio spectral index and misalignment between the jets and ionised optical emission suggested that the orientation of the QSO had recently changed. We use a combination of new, multi-band Giant Metrewave Radio Telescope observations and archival radio data to confirm that the jets are no longer powered by the QSO, and estimate their age to be 120-160 Myr. This is in agreement with the ~70-200 Myr age previously estimated for star-formation in the galaxy. Previously unpublished Very Long Baseline Array data reveal a 200 pc scale double radio source in the galaxy core which is more closely aligned with the current QSO axis and may represent a more recent period of jet activity. These results suggest that the realignment of the QSO, the cessation of jet activity, and the onset of rapid star-formation may have been caused by a gas-rich galaxy merger. A Chandra X-ray observation confirms the presence of cavities associated with the radio jets, and we estimate the energy required to inflate them to be ~7.7x10^60 erg. The mechanical power of the jets is sufficient to balance radiative cooling in the cluster, provided they are efficiently coupled to the intra-cluster medium (ICM). We find no evidence of direct radiative heating and conclude that the QSO either lacks the radiative luminosity to heat the ICM, or that it requires longer than 100-200 Myr to significantly impact its environment. 

Read more (617kb, PDF)



__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Cosmology News -> IRAS 09104+4109


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard